I try not to think about regrets and instead focus on what I can change moving forward. Everyone's life is full of various regret and unfortunately without a time machine you and undo mistakes.
But If i had to choose one, probably being stupid with money when I was in my 20s. Its was a fun decade but expensive and Im still paying for all these years later.
I think that lack of confidence that you mentioned is usually the root of any answer to this question. Personally, I think that sounds like an enriching experience that not many people ever get. You can always educate yourself and do more and maybe you have a certain work ethic from your upbringing that you can take with you wherever you go. My main regret is not taking more risks when I was younger and just doing what my parents wanted which was to go to school. I'm still glad I went but I wasted a lot of time taking classes that would never benefit me.
.Personally, my biggest regret is dropping out of school to work on my father's farm.
And in a few years, when things go to shit, your farm will have something a lot of people won't have: food. If you can do school online and part time, go for it. But you as a farmer have advantages the rest of us don't have.